The 7th Hendon is not mentioned in the 1957 Hendon Local Association booklet that marked 50 years of Scouting, because there was no Group in existence at that time designated as such. Because Groups were usually numbered consecutively it is fair to say that such a Group probably did exist at one time but closed prior to 1957.
The Group does however appear in the District Directory, dated June 1965, and is recorded as meeting at the Jewish Reform Synagogue, Danescroft Gardens, Hendon NW4. Their scarf was pale blue and white halves. The GSM is noted as being M Posner, the SM as D Seres and the CM as P Simonis.